The death of Valens and the consequences
In the rout, the emperor himself was abandoned by his guards. Some tried to retrieve him but the majority of the cavalry deserted. He died anonymously on the field.
According to the historian Ammianus Marcellinus a third of the Roman army succeeded in retreating, but the losses were uncountable. Many officers, among them the general Sebastian, were killed in the worst Roman defeat since the Battle of Cannae. The battle was a devastating blow for the late empire. In effect, the core of the eastern empire was destroyed, valuable administrators were killed, and all of the arms factories on the Danube were destroyed following the battle. The lack of reserves for the army led to a recruitment crisis, which accentuated the strategic and moral impact of the defeat.
The battle signified that the barbarians, fighting for or against the Romans, had become powerful adversaries. The crisis that began in 376 was relieved only by negotiations in 382. Theodosius I, Valens' successor, accepted the Goths once more as allies. This compromise left the door open for other Gothic mutinies.
The end of Antiquity?
Some historians give the Battle of Adrianople as the end of Antiquity and the beginning of the Middle Ages. They see in the battle the advent of heavy cavalry and the decline of the infantry, marking the beginning of a thousand years of superiority of cavalry over infantry.
Further Reading